1. Field of the Invention (Technical Field)
The invention relates to heating system controls and more particularly to an apparatus and method of controlling hydronic and gas-fired hot-water space-heating systems utilizing DC or battery power.
2. Background Art
Control devices for heating systems are not new in the art. However, systems that are presently available utilize AC power sources that require standby electrical loads. These systems are inherently inefficient. Some prior art references illustrate this.
U.S. Pat. No. 5,622,221 to Genga, Jr., et al. discloses a control device for a multi zone hydronic boiler heating system using zone pumps. Genga, Jr. et al. discloses control system circuitry that is integrated into each individual zone pump requiring data-buss wiring between the pumps. The present invention is a central control system requiring only 2-conductor electric power wiring to the pumps. The main purpose of this prior art system is to provide priority zone control that is easily programmed using switches on the pumps, while the present invention can be wired to provide switchable priority control from the central control box. This control system requires 115 Volt AC as its primary power supply, while the present invention uses DC batteries for primary power. This control system requires low voltage transformers mounted on every pump, while the present invention eliminates most or all transformers.
U.S. Pat. No. 5,739,504 to Lyons, et al., teaches the control of the time duration of the operation of the flame in a boiler. The main purpose of Lyons' device is to allow accurate water level monitoring for steam boilers. The present invention is external to the boiler, and does not require alteration of any OEM wiring and allows the internal boiler controls to control the flame as installed by the manufacturer. The invention's time control circuit turns external power to the entire boiler on and off, not just the internal gas flame.
U.S. Pat. No. 4,474,325 to Richardson describes an internal control system that allows a hydronic boiler to be used to generate hot air for space heating. It includes electrical controls for a boiler, a pump, a fan, and a heat exchanger with safety controls for the gas flame. The control system is powered by AC 120 volt electricity through a transformer.
U.S. Pat. No. 5,881,681 to Stuart describes the internal components and controls of a hydronic boiler. The controls monitor the conditions inside the boiler and regulate the water temperature by modulating the flame combustion process.
U.S. Pat. No. 5,592,989 to Lynn, et al., allows thermostatic control of a number of electrical heating components that need several different voltages. This system is intended especially for fan coil unit heaters. This system uses special electronic thermostats with up to 13 signal wire connections, and is designed to control only AC voltages.
U.S. Pat. No. 4,349,148 to Liberto, et al., discloses a system and components needed to operate a hot air furnace using batteries as a temporary emergency power supply. This system uses DC batteries and a secondary power control circuit as a backup system when conventional AC power is unavailable, while the present invention uses DC batteries as the primary and continuous power supply and the control circuit as the primary heating system control. In addition, the present invention is designed around water circulator pumps, rather than fans, and the pumps are DC continuous, rather than auxiliary duty. The secondary power control circuit in the Liberto patent utilizes a complex arrangement of 3 inverters, to provide AC power to emergency relays, gas valve, and auxiliary DC fan.
U.S. Pat. No. 4,946,096 to Ballard, et al., discloses an emergency system that forces the furnace into a low electrical power demand mode when running on battery power, by disabling portions of the heating system when operating on battery power.
U.S. Pat. No. 4,673,826 to Masson describes a DC battery power supply that is controlled by digital microprocessors to provide power primarily for computers. This system uses digital command signals in response to a variety of system conditions, such as the state-of-charge of the batteries, the quality of the inverter output, and the presence or absence of conventional AC power.
U.S. Pat. No. 4,978,063 to Chase describes a configuration of relays that locks out the space heating zones whenever the domestic hot water heater calls for heat. This type of circuit is commonly known as a "Hot Water Priority" circuit because it gives priority to heating the water tank first, and then allows space heating only after the tank is hot.
U.S. Pat. No. 4,400,626 to Lacy describes a system developed mainly for aircraft application that reduces the electric power consumption during emergency power failure conditions by disconnecting non-critical electric loads.
None of the prior art, however, discloses a DC control unit as the primary source of power for the heating system to run at full capacity with high electric efficiency, little standby electric demand and continuous duty.